Earlier quoted context omitted.
The alternative is to not have a cheap popular bikeshare system. Also with monopolist it is really easy to keep some standards, quality of the ads.
False dichotomy. The alternative is to have a cheap popular bikeshare system supported by taxes. [Edit to reply to okr, because I'm rate-limited: Well, then, make the users of the bikes pay the full cost of the bike service. As it is, you're pushing ads in everyone's face, whether or not they use the bike. Also no thanks.]
Great, so long as motorists pay the full cost of the roads.